JP6243724B2 - Magnetic sensor with hall element and signal correction method thereof - Google Patents

Description

The present invention relates to a magnetic sensor and a signal correction method with a Hall element.

Conventionally, as a magnetic sensor semiconductor integrated circuit incorporating a Hall element, a current sensor that detects a magnetic field generated by a current, a rotation angle sensor that detects rotation of a magnet, a position sensor that detects movement of a magnet, and the like have been known. Yes.
FIG. 1 is a diagram illustrating an example of a drive circuit for a Hall element. It can be seen that a Hall element output V _H is obtained between the electrode 2 and the electrode 4 when a hall driving current I _{H is} passed from the electrode 1 to the electrode 3.

Generally, there are two types of driving methods for the Hall element: a constant current driving method and a constant voltage driving method. The constant current driving method is a method in which the hall driving current _IH is always constant in FIG. 1, and the constant voltage driving method is a method in which the hall driving voltage _Vd is constant. The magnetic sensitivity in each driving method is expressed as constant current sensitivity and constant voltage sensitivity.
In general, the Hall element has a configuration in which an n-type impurity region is provided on the surface of a p-type semiconductor substrate layer made of p-type silicon, and this n-type impurity region functions as a magnetic sensing portion.

  For example, the device described in Patent Document 1 relates to a vertical Hall element that can increase the degree of freedom of selection of a substrate used for forming the Hall element, and a manufacturing method thereof. The vertical Hall element is formed on a semiconductor substrate made of P-type silicon, and a current including a component perpendicular to the surface of the substrate is supplied to the magnetic detection unit HP in the N-type semiconductor region 12. When a magnetic field component parallel to the surface of the substrate is applied to the magnetic detector HP, a Hall voltage signal corresponding to the magnetic field component is output.

In Patent Document 2, 1.0 × 10 ¹⁶ ≦ N ≦ 3.0 × 10 ¹⁶ (atoms / cm ³ ) is suitable as the concentration of the n-type impurity region suitable for the azimuth angle sensor for the purpose of improving SN. It is disclosed.
Patent Document 3 discloses a method for performing a five-temperature inspection in a pre-shipment test, writing the result into an EEPROM, correcting a broken line at a five-point temperature, and increasing the detection magnetic field accuracy. .

Further, Patent Document 4 describes the concentration distribution in the depth direction of the N-type region of the electrode portion of the Hall element, and in the depth direction when the concentration distribution range, that is, the substrate surface is used as a base point. It is disclosed that the concentration of the N-type impurity is 5 × 10 ¹⁷ atoms / cm ³ or more and 3 × 10 ¹⁹ atoms / cm ³ or less within a range of 0.3 μm or more and 0.5 μm or less.

JP 2005-333103 A International Publication No. WO2007 / 116823 US 2012/0086442 Specification JP 2012-204616 A

It is known that the magnetic sensitivity of the Hall element varies depending on the temperature as described in Patent Document 3, for example. Since the temperature change of the magnetic sensitivity leads to a decrease in the magnetic field detection accuracy, it is necessary to correct the temperature characteristics of the magnetic sensitivity of the Hall element in order to calculate the magnetic field strength with high accuracy.
The relationship between the output of the Hall element and the magnetic field strength is expressed by Equation (1). When the constant current sensitivity is SI (T), the drive current of the Hall element is I _H , and the magnetic field strength is B, the signal obtained from the Hall element is Signal (T) in Equation (1). Since the constant current sensitivity SI (T) has temperature dependence, in order to calculate the magnetic field strength B with high accuracy, it is necessary to divide by a coefficient proportional to the temperature dependence of the constant current sensitivity.

  The temperature characteristic of the constant current sensitivity of the conventional Hall element has a secondary characteristic. Therefore, the output when the conventional Hall element is placed in a constant magnetic field has a second-order temperature characteristic as shown in Equation (2).

As shown in Equation (2), in order to calculate a magnetic field with high accuracy from a signal having secondary temperature characteristics, it is necessary to have a secondary function of temperature as a correction function.
In recent years, a highly accurate magnetic sensor has been demanded, and in particular, as a vehicle-mounted magnetic sensor, a magnetic sensor having a residual correction error of 1.0% or less between −40 degrees and 150 degrees is desired. Here, the correction remaining error E _R is the value represented by the following formula.

E _R = (SI _MAX -SI _MIN ) / 2
SI _MAX is the maximum magnetic sensitivity among the corrected magnetic sensitivities from −40 degrees to 150 degrees, and SI _MIN is the minimum magnetic sensitivity among the corrected magnetic sensitivities from −40 degrees to 150 degrees. . SI _MAX and SI _MIN are both values normalized by the corrected magnetic sensitivity at 25 degrees. Correction as the remaining error E _R is large, it becomes possible to have variations in magnetic sensitivity after correction at 150 ° -40 °, the more the correction remaining error E _R is small, the magnetic sensitivity corrected at 150 ° -40 ° It will not vary.

  In the case of a magnetic sensor using a conventional Hall element, an accurate correction function for correcting the temperature characteristic of magnetic sensitivity is used in order to make the residual correction error between -40 degrees and 150 degrees less than 1.0%. It is necessary to obtain a quadratic correction function. In order to calculate an accurate second-order correction function, the magnetic sensitivity of the Hall element must be measured at a number of temperatures. In the case of a conventional Hall element, the test process for calculating the correction function is extremely numerous. It took time and money.

In addition, the number of magnetic sensitivity measurements for calculating the correction function and the magnetic detection accuracy are in a trade-off relationship. In the case of a conventional Hall element, if the number of magnetic sensitivity measurements is reduced, the magnetic detection accuracy decreases, and − There is a problem in that the residual correction error cannot be reduced to 1.0% or less between 40 degrees and 150 degrees.
The present invention has been made in view of such circumstances, and an object, the magnetic having a hole element which can be determined by measuring the number of magnetic sensitivity less correction function with sufficient accuracy It is to provide a sensor and a signal correction method thereof.

The present invention has been made to achieve such an object. The present invention includes a p-type impurity region and an n-type impurity region provided on the p-type impurity region and functioning as a magnetically sensitive portion. A magnetic sensor comprising a Hall element having an n-type impurity concentration N (atoms / cm ³ ) and a distribution depth D (μm) of the n-type impurity region,
N <1.0 × 10 ¹⁶
N> 3.802 × 10 ¹⁶ × D ^−1.761
(However, the n-type impurity concentration N is the maximum concentration of the n-type impurity concentration in the n-type impurity region, and the distribution depth D is determined from the point that the n-type impurity concentration becomes maximum. (This is the length in the depth direction up to the point where the impurity concentration is 1/10 of the concentration.)
Meet the relationship, correction and temperature characteristic storage unit in which information relating to the temperature characteristic has been stored in the Hall element, the output of the temperature sensor, based on the information on the temperature characteristics of the Hall element, the output of the Hall element A correction signal generating unit for generating a correction signal for generating the correction signal, the correction signal generated by the correction signal generating unit, and the output signal of the Hall element are input, and the output signal of the Hall element based on the correction signal And a signal correction unit for correcting .

  According to the present invention, since the temperature characteristic of the magnetic sensitivity of the Hall element is substantially linear, the correction for correcting the temperature characteristic of the magnetic sensitivity from the result of measuring the magnetic sensitivity at two temperatures of −40 degrees and 150 degrees. Even when the function is created, the correction function is sufficiently accurate. According to the first aspect of the present invention, it is possible to provide a Hall element capable of obtaining a correction function having sufficient accuracy with a small number of magnetic sensitivity measurements.

Further, the present invention is characterized in that the n-type impurity concentration N and the distribution depth D satisfy a relational expression of N> 3.410 × 10 ¹⁶ × D− ^1.293 .
According to the present invention, since the temperature characteristic of the magnetic sensitivity of the Hall element is substantially linear, a correction function for correcting the temperature characteristic of the magnetic sensitivity from the result of measuring the magnetic sensitivity at two temperatures of 25 degrees and 150 degrees. It is possible to create a sufficiently accurate correction function even when According to the second aspect of the present invention, it is possible to provide a Hall element capable of obtaining a correction function having sufficient accuracy with a small number of magnetic sensitivity measurements.

Further, the present invention is characterized in that the distribution depth D satisfies a relational expression of D ≦ 15.
Further, the present invention is characterized in that the distribution depth D satisfies a relational expression of 4 ≦ D.
According to the present invention, it is possible to reduce the residual offset remaining after driving the 2Phase chopper.
The present invention is further characterized by further comprising a silicon oxide layer covering the n-type impurity region.

According to the present invention, a large depletion layer does not occur at the connection portion between the silicon oxide layer and the n-type impurity region. Thereby, the linearity of the temperature characteristic of the magnetic sensitivity of the Hall element can be improved.
Further, the present invention is characterized in that the n-type impurity region and the silicon oxide layer are in contact with each other.

According to the present invention, a large depletion layer does not occur at the connection portion between the silicon oxide layer and the n-type impurity region. Thereby, the linearity of the temperature characteristic of the magnetic sensitivity of the Hall element can be improved.
Further, the present invention is characterized in that the n-type impurity concentration N satisfies a relational expression of 3.0 × 10 ¹⁴ <N.

Also, the present invention, the temperature characteristic storage unit includes a temperature-proportional coefficient storage unit in which information relating to the temperature proportional coefficient of the magnetic sensitivity of the Hall element is stored, information about the magnetic sensitivity at a given temperature of the Hall element A magnetic sensitivity storage unit that stores information, and the information on the temperature characteristics of the Hall element includes information on a temperature proportionality coefficient of the magnetic sensitivity of the Hall element and information on the magnetic sensitivity of the Hall element at a predetermined temperature. It is characterized by.

According to the present invention, it is possible to accurately correct the output change of the Hall element due to the temperature change using the temperature proportionality coefficient of the Hall element magnetic sensitivity and the magnetic sensitivity of the Hall element at a predetermined temperature. .
Further, in the present invention, the information related to the temperature proportionality coefficient of the magnetic sensitivity of the Hall element stored in the temperature proportionality coefficient storage unit is information related to the temperature proportionality coefficient of the constant current sensitivity of the Hall element, and the magnetic sensitivity storage unit The information on the magnetic sensitivity at a predetermined temperature of the Hall element stored in is the information on the constant current sensitivity of the Hall element at the predetermined temperature.

According to the present invention, it is possible to accurately correct the output change of the Hall element due to the temperature change using the temperature proportionality coefficient of the constant current sensitivity of the Hall element and the constant current sensitivity of the Hall element at a predetermined temperature. It becomes.
Further, according to the present invention, the information regarding the temperature proportionality coefficient of the magnetic sensitivity of the Hall element includes the first magnetic sensitivity of the Hall element measured at a first temperature and the Hall element measured at a second temperature. It is the information calculated from the second magnetic sensitivity.

In the present invention, the first magnetic sensitivity is a constant current sensitivity of the Hall element measured at the first temperature, and the second magnetic sensitivity is measured at the second temperature. The Hall element has a constant current sensitivity.
According to the present invention, the information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element further includes the Hall element measured at the first magnetic sensitivity, the second magnetic sensitivity, and the third temperature. The third magnetic sensitivity is information calculated from the third magnetic sensitivity.

In the invention, it is preferable that the third magnetic sensitivity is a constant current sensitivity of the Hall element measured at the third temperature.
Further, the present invention is characterized in that the information related to the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is calculated from the magnetic sensitivity of the Hall element measured at a temperature of 2 to 5 points.

According to the present invention, it is possible to provide a magnetic sensor having sufficient magnetic field detection accuracy with a small number of test steps.
Further, the present invention is characterized in that the information related to the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is calculated from the magnetic sensitivity of the Hall element measured at a temperature of 2 to 3 points.

According to the present invention, it is possible to provide a magnetic sensor having sufficient magnetic field detection accuracy with a small number of test steps.
Further, the present invention is characterized in that the information on the temperature characteristics of the Hall element is calculated from the output of the Hall element measured at a temperature of 2 to 5 points.
According to the present invention, it is possible to provide a magnetic sensor having sufficient magnetic field detection accuracy with a small number of test steps.

Further, the present invention is characterized in that the information on the temperature characteristics of the Hall element is calculated from the output of the Hall element measured at a temperature of 2 to 3 points.
According to the present invention, it is possible to provide a magnetic sensor having sufficient magnetic field detection accuracy with a small number of test steps.
The present invention is also a method for correcting a signal of a magnetic sensor, wherein the Hall sensor is based on a step of obtaining information on temperature characteristics of the Hall element, an output of the temperature sensor, and information on temperature characteristics of the Hall element. Generating a correction signal for correcting the output of the element, obtaining the output of the Hall element, and correcting the output signal of the Hall element using the correction signal, To do.

According to the present invention, high-precision magnetic field detection can be performed with a small number of test steps.
In the present invention, the information on the temperature characteristics of the Hall element includes information on a temperature proportionality coefficient of the magnetic sensitivity of the Hall element and information on a magnetic sensitivity of the Hall element at a predetermined temperature, and the temperature characteristic of the Hall element The step of acquiring the information on the magnetic field includes the step of acquiring information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element and information on the magnetic sensitivity of the Hall element at a predetermined temperature.

According to the present invention, it is possible to accurately correct the output change of the Hall element due to the temperature change using the temperature proportionality coefficient of the Hall element magnetic sensitivity and the magnetic sensitivity of the Hall element at a predetermined temperature. .
Further, in the present invention, the information related to the temperature proportionality coefficient of the Hall element magnetic sensitivity is information related to the temperature proportional coefficient of the constant current sensitivity of the Hall element, and the information related to the magnetic sensitivity of the Hall element at a predetermined temperature is It is the information regarding the constant current sensitivity of the said Hall element in the said predetermined temperature, It is characterized by the above-mentioned.

According to the present invention, it is possible to accurately correct the output change of the Hall element due to the temperature change using the temperature proportionality coefficient of the constant current sensitivity of the Hall element and the constant current sensitivity of the Hall element at a predetermined temperature. It becomes.
Further, according to the present invention, the information regarding the temperature proportionality coefficient of the magnetic sensitivity of the Hall element includes the first magnetic sensitivity of the Hall element measured at a first temperature and the Hall element measured at a second temperature. It is the information calculated from the second magnetic sensitivity.

In the present invention, the first magnetic sensitivity is a constant current sensitivity of the Hall element measured at the first temperature, and the second magnetic sensitivity is measured at the second temperature. The Hall element has a constant current sensitivity.
According to the present invention, the information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element further includes the Hall element measured at the first magnetic sensitivity, the second magnetic sensitivity, and the third temperature. The information is calculated from the third magnetic sensitivity.

In the invention, it is preferable that the third magnetic sensitivity is a constant current sensitivity of the Hall element measured at the third temperature.
Further, the present invention is characterized in that the information related to the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is calculated from the magnetic sensitivity of the Hall element measured at a temperature of 2 to 5 points.

According to the present invention, it is possible to detect a magnetic field with high accuracy with a small number of test steps.
Further, the present invention is characterized in that the information related to the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is calculated from the magnetic sensitivity of the Hall element measured at a temperature of 2 to 3 points.
According to the present invention, it is possible to detect a magnetic field with high accuracy with a small number of test steps.

Further, the present invention is characterized in that the information on the temperature characteristics of the Hall element is calculated from the output of the Hall element measured at a temperature of 2 to 5 points.
According to the present invention, it is possible to detect a magnetic field with high accuracy with a small number of test steps.
Further, the present invention is characterized in that the information on the temperature characteristics of the Hall element is calculated from the output of the Hall element measured at a temperature of 2 to 3 points.

According to the present invention, it is possible to detect a magnetic field with high accuracy with a small number of test steps.
According to the present invention, the step of obtaining information on the temperature characteristics of the Hall element includes measuring the first magnetic sensitivity of the Hall element at a first temperature, and measuring the first magnetic sensitivity of the Hall element at a second temperature. And measuring information on a temperature proportionality coefficient of the Hall element from the first magnetic sensitivity and the second magnetic sensitivity, and measuring the magnetic sensitivity of the temperature sensor. The step of generating a correction signal for correcting the output of the Hall element based on the output and the information on the temperature characteristic of the Hall element includes the output of the temperature sensor and the temperature proportional coefficient of the magnetic sensitivity of the Hall element. And a step of generating a correction signal for correcting the output of the Hall element based on the information on the magnetic field and the magnetic sensitivity of the Hall element at a predetermined temperature. Characterized in that it is a flop.

According to the present invention, it is possible to accurately correct the output change of the Hall element due to the temperature change using the temperature proportionality coefficient of the Hall element magnetic sensitivity and the magnetic sensitivity of the Hall element at a predetermined temperature. .
According to the present invention, the step of obtaining information on the temperature characteristics of the Hall element includes measuring the first magnetic sensitivity of the Hall element at a first temperature, and measuring the first magnetic sensitivity of the Hall element at a second temperature. Measuring the second magnetic sensitivity, measuring the third magnetic sensitivity of the Hall element at a third temperature, the first magnetic sensitivity, the second magnetic sensitivity, and the third magnetic sensitivity. And acquiring information related to a temperature proportionality coefficient of the magnetic sensitivity of the Hall element, and correcting the output of the Hall element based on the output of the temperature sensor and the information related to the temperature characteristic of the Hall element. Generating a correction signal for detecting the output of the temperature sensor, information on a temperature proportionality coefficient of the magnetic sensitivity of the Hall element, and the home sensor at a predetermined temperature. Based on the magnetic sensitivity of Le element, characterized in that it is a step of generating a correction signal for correcting the output of the Hall element.

According to the present invention, it is possible to accurately correct the output change of the Hall element due to the temperature change using the temperature proportionality coefficient of the Hall element magnetic sensitivity and the magnetic sensitivity of the Hall element at a predetermined temperature. .
Further, the present invention is characterized in that the magnetic sensitivity is a constant current sensitivity.
Further, in the present invention, the step of obtaining information on the temperature characteristics of the Hall element is a process performed before shipment, and the Hall element is based on the output of the temperature sensor and the information on the temperature characteristic of the Hall element. A step of generating a correction signal for correcting the output of the Hall element, a step of acquiring the output of the Hall element, and a step of correcting the output signal of the Hall element using the correction signal are performed during magnetic field measurement. It is a process.

According to the present invention, it is possible to provide a magnetic sensor and a signal correction method comprising a Hall element which can be determined by measuring the number of magnetic sensitivity less correction function with sufficient accuracy.

It is a figure which shows the drive circuit example of a Hall element. (A), (b) is the top view (layout) and sectional drawing of a Hall element used for the magnetic sensor of this invention. It is a figure which shows the relationship between depth and n-type impurity concentration. It is a figure which shows the relationship between distribution depth and n-type impurity region density | concentration. It is a block block diagram for demonstrating embodiment of the magnetic sensor which concerns on this invention. It is a figure which shows the flowchart for demonstrating embodiment of the signal correction method of the magnetic sensor which concerns on this invention shown in FIG. It is a figure which shows the flowchart for demonstrating Example 1 of the signal correction method of the magnetic sensor which concerns on this invention shown in FIG. It is a figure which shows the relationship of the linear approximation error with respect to n-type impurity concentration. It is a schematic sectional drawing at the time of operation | movement of a Hall element. It is a figure which shows the relationship between distribution depth and n-type impurity region density | concentration. It is a schematic sectional drawing at the time of operation | movement of a Hall element. It is a figure which shows the flowchart for demonstrating Example 2 of the signal correction method of the magnetic sensor which concerns on this invention shown in FIG. It is a figure which shows the relationship of the 3-point broken line approximation error with respect to n-type impurity concentration. It is a figure which shows the relationship between the distribution depth in Example 3, and the dispersion | variation in a residual offset. It is a figure which shows the relationship between distribution depth and n-type impurity region density | concentration. It is a figure which shows the flowchart for demonstrating Example 4 of the signal correction method of the magnetic sensor which concerns on this invention shown in FIG. It is a figure which shows the relationship of the temperature characteristic variation of the constant current sensitivity with respect to n-type impurity concentration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As a technique for realizing a high-accuracy magnetic sensor, the present invention realizes a method for limiting the concentration and depth of the n-type impurity region of the magnetic sensing portion of the Hall element to an appropriate range and correcting the temperature characteristics of the magnetic sensitivity. It is aimed.
2A and 2B are configuration diagrams for explaining the Hall element according to the present invention. FIG. 2A is a top view of the Hall element, and FIG. 2B is a plan view of FIG. It is a CD sectional view taken on the line. In the figure, reference numeral 1 denotes a p-type impurity region, 2 denotes an n-type impurity region, and 3 denotes an n-type region (electrode part). The n-type impurity region 2 functions as a magnetic sensing portion of the Hall element, and the n-type region 3 functions as an electrode of the Hall element.

The Hall element of the present embodiment includes a p-type impurity region 1 and an n-type impurity region 2 provided on the p-type impurity region 1 and functioning as a magnetic sensitive part.
In this embodiment, the maximum n-type impurity concentration in the n-type impurity region is defined as an n-type impurity concentration N. From the point that the n-type impurity concentration becomes maximum, the n-type impurity concentration is the n-type impurity concentration N. The length in the depth direction up to a point that becomes 1/10 is defined as the distribution depth D. The unit of n-type impurity concentration N is atoms / cm ³ and the unit of distribution depth D is μm.

Note that secondary ion mass spectrometry (SIMS) is used to measure the maximum n-type impurity concentration N and the distribution depth D in the n-type impurity region. In this method, ions are made incident on the sample surface, ions released from the sample surface are detected, and the detection amount at each mass is measured to qualitatively and quantitatively determine the components contained in the sample. By this measurement, for example, the concentration of the n-type impurity concentration in the cross-sectional direction as shown in FIG. 4 can be measured. The measurement device is “CAMECA IMS-7f”, and the measurement conditions are primary ion species: Cs +, secondary ion polarity: negative, and acceleration voltage: 15.0 kV.
The n-type impurity concentration N (atoms / cm ³ ) and the distribution depth D (μm) of the n-type impurity region 2 satisfy the following formula (3).

However, the n-type impurity concentration N is the maximum concentration of the n-type impurity concentration in the n-type impurity region, and the distribution depth D is 1/10 of the n-type impurity concentration N in view of the maximum n-type impurity concentration. It is the length in the depth direction up to the point where the density becomes.
In the Hall element of the present embodiment satisfying the above mathematical formula (3), the temperature characteristic of the magnetic sensitivity is substantially linear, and thus a correction function created from the result of measuring the magnetic sensitivity at two temperatures of −40 degrees and 150 degrees. Even so, the correction function is sufficiently accurate.

More specifically, even when the magnetic sensitivity in the range of −40 degrees to 150 degrees is corrected using a correction function created from the result of measuring the magnetic sensitivity at two temperatures of −40 degrees and 150 degrees, The remaining correction error can be reduced to 1.0% or less.
FIG. 3 is a diagram showing the relationship between the distribution depth D and the n-type impurity concentration N. As shown in FIG. As shown in FIG. 3, the concentration of the N-type impurity in the n-type impurity region is generally lower in concentration near the surface of the silicon substrate, and the concentration becomes lower as the depth increases. In FIG. 3, all the n-type impurity concentrations N are 1.0 × 10 ¹⁶ (atoms / cm ³ ), and the distribution depths D are 8 μm, 6 μm, and 4 μm, respectively.
Furthermore, the n-type impurity concentration N and the distribution depth D of the n-type impurity concentration in the n-type impurity region satisfying Expression (4) are more preferable.

In the Hall element of the present embodiment satisfying the above mathematical formula (4), the temperature characteristic of the magnetic sensitivity is substantially linear, so a correction function created from the result of measuring the magnetic sensitivity at two temperatures of 25 degrees and 150 degrees. Even if it exists, it becomes a sufficiently accurate correction function.
More specifically, even when the magnetic sensitivity in the range of −40 degrees to 150 degrees is corrected using the correction function created from the result of measuring the magnetic sensitivity at two temperatures of 25 degrees and 150 degrees, the correction is performed. The remaining error can be reduced to 1.0% or less.

FIG. 4 is a diagram illustrating the relationship between the distribution depth and the n-type impurity region concentration, and is a diagram illustrating the ranges indicated by Equation (3) and Equation (4).
Next, the basis will be described.
FIG. 5 is a block diagram for explaining an embodiment of the magnetic sensor according to the present invention. In the figure, reference numeral 21 denotes a hall element, 22 denotes a hall driving current source, 23 denotes a chopper switch unit, 24 denotes a differential amplifier, 25 denotes an integrator, 26 denotes a temperature sensor, 27 denotes an analog-digital converter (ADC), and 28 denotes a temperature. A proportional coefficient storage unit (EEPROM), 29 is a magnetic sensitivity storage unit (EEPROM), 30 is a correction signal generation unit, 31 is a signal correction unit, and 32 is a temperature characteristic storage unit. The temperature characteristic storage unit 32 includes a temperature proportionality coefficient storage unit 28 and a magnetic sensitivity storage unit 29. The information on the temperature characteristics of the Hall element includes information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element and information on the magnetic sensitivity of the Hall element at a predetermined temperature. Hereinafter, the magnetic sensitivity of the Hall element will be described as constant current sensitivity. However, the magnetic sensitivity of the Hall element is not limited to constant current sensitivity, and may be constant voltage sensitivity, for example.

  The magnetic sensor of the present invention is a magnetic sensor including the Hall element shown in FIG. The hall drive current source 22 is a current source that drives the hall element 21 at a constant current. The chopper switch unit 23 is a switch group for driving the Hall element 21 by 2 Phase chopper driving or 4 Phase chopper driving. By integrating the chopper-driven signal with the integrator 25, the offset of the Hall element 21 can be dynamically removed as shown in Equation (5).

  An example of 4 Phase chopper driving is as follows: a Hall driving current is passed from Electrode 1 to Electrode 3 at Phase 1, Electrode 2-Electrode 4 is connected to a differential amplifier, and a Hall driving current is applied from Electrode 2 to Electrode 4 at Phase 2. The electrode 3-electrode 1 is connected to the differential amplifier 14, a hall driving current is passed from the electrode 3 to the electrode 1 at Phase 3, the electrode 4-electrode 2 is connected to the differential amplifier 24, and the electrode 4 is connected to the electrode at Phase 4 The driving procedure is such that a hall driving current is supplied to 2 and the electrodes 1 to 3 are connected to the differential amplifier 24.

The differential amplifier 24 amplifies (α times) the output difference of the Hall element 21. The integrator 25 is an integrator that moves in synchronization with the chopper drive, and adds the outputs of the differential amplifiers 24 of each phase.
The temperature sensor 26 is a sensor that measures the temperature on the silicon substrate, and the ADC 27 changes the output signal T of the temperature sensor 26 into a digital signal. The temperature proportionality coefficient storage unit 28 stores the temperature proportionality coefficient of the constant current sensitivity of the Hall element 21, and the magnetic sensitivity storage unit 29 stores the absolute value (one-point temperature) of the constant current sensitivity of the Hall element 21. To do. The correction signal generation unit 30 uses the signal β obtained from the temperature proportional coefficient storage unit 28, the signal SI (25) obtained from the magnetic sensitivity storage unit 29, and the signal T obtained from the temperature sensor 26 to output the output of the Hall element 21. The correction signal β (T) is generated. The signal correction unit 31 corrects the output signal of the Hall element 21 using β (T) obtained from the correction signal generation unit 30.

Further, the linear correction magnetic sensor (corresponding to the signal correction method of Example 1 described later) has the correction signal generation unit 30 that has the first constant current sensitivity SI25 measured at the first temperature of 25 ° C. and the second constant current sensitivity SI25. A correction coefficient β (T) is generated based on the slope β calculated from the second constant current sensitivity SI150 measured at a temperature of 150 ° C.
In addition, the three-point correction magnetic sensor (corresponding to a signal correction method of Example 2 described later) includes a first constant current sensitivity SI25 measured by the correction signal generator 30 at a first temperature of 25 ° C. The first slope β1 calculated from the second constant current sensitivity SI150 measured at the second temperature 150 ° C. and the third constant current sensitivity SI-40 measured at the third temperature −40 ° C. The correction coefficient β (T) is generated based on the gradient β2 of 2.

In addition, as a two-phase drive magnetic sensor (corresponding to a signal correction method of Example 3 described later), the chopper switch unit 23 is driven in two phases.
In addition, the tilt correction magnetic sensor (corresponding to a signal correction method according to Example 4 described later) has a correction signal generation unit 30 that has a first constant current sensitivity SI25 measured at a first temperature of 25 ° C. and a second constant current sensitivity SI25. The slope β calculated from the second constant current sensitivity SI150 measured at a temperature of 150 ° C. is determined in advance, and the first constant current sensitivity SI25 measured at the first temperature of 25 ° C. is determined in advance. A correction coefficient β (T) is generated based on the slope β.

FIG. 6 is a flowchart for explaining an embodiment of the signal correction method of the magnetic sensor according to the present invention shown in FIG. The signal correction method for the magnetic sensor of the present invention is a signal correction method for the magnetic sensor including the Hall element shown in FIG.
Step S101 for switching the hall driving current between the electrodes of the Hall element 21 by the chopper switch unit 23, Step S102 for amplifying the difference of the output from the chopper switch unit 23 by the differential amplifier 24, and the chopper switch unit 23 There is a step S103 that operates in synchronization with the chopper drive and adds the output of the differential amplifier 24 by the integrator 25.

Further, step S104 for measuring the temperature on the substrate on which the hall element is mounted by the temperature sensor 26, step S105 for storing the temperature proportional coefficient of the constant current sensitivity of the hall element 21 by the temperature proportional coefficient storage unit 28, and hall Step S106 for storing the absolute value of the constant current sensitivity of the element 21 by the magnetic sensitivity storage unit 29.
Further, a correction signal β (T) of the output of the Hall element 21 is obtained by using the signal β obtained from the temperature proportional coefficient storage unit 28, the signal SI25 obtained from the magnetic sensitivity storage unit 29, and the signal T obtained from the temperature sensor 26. Step S107 generated by the correction signal generation unit 30 and Step S108 of correcting the output signal of the Hall element 21 by the signal correction unit 31 using the signal β (T) obtained from the correction signal generation unit 30. .

As each signal correction method described below, the simpler as possible, the smaller the circuit scale and the fewer the EEPROM, and the cost can be reduced. The signal correction described below includes correction of a physical quantity based on Hall electromotive force. That is, the physical quantity based on the Hall electromotive force can include a Hall electromotive force signal V _H , constant current sensitivity SI (T), Hall drive current I _H , magnetic field B, and an amount proportional to each physical quantity. .

  FIG. 7 is a flowchart for explaining the first embodiment of the signal correction method of the magnetic sensor according to the present invention shown in FIG. 5, and shows the flow of determination of correction coefficients and correction. In the first embodiment, a constant current sensitivity is measured at 25 ° C. and 150 ° C. in a pre-shipment inspection, and a two-point linear approximation method is used for correction. Further, the signal correction method of the magnetic sensor in the first embodiment includes a step (A) for performing a test (output inspection) before shipment and a step (B) for performing the magnetic field measurement.

  In the step (A) for performing the test before shipment, first, the first constant current sensitivity SI25 at the first temperature of 25 ° C. is measured (step S1). Next, the second constant current sensitivity SI150 at the second temperature of 150 ° C. is measured (step S2). Next, the slope β is calculated from the first constant current sensitivity SI25 and the second constant current sensitivity SI150 (step S3). Next, the inclination β is stored in the temperature proportional coefficient storage unit 28 (step S4). Next, the first constant current sensitivity SI25 is stored in the magnetic sensitivity storage unit 29 (step S5).

In the step (B) executed at the time of magnetic field measurement, first, the temperature T is measured by the temperature sensor 26 (step S6). Next, the temperature T is AD converted (step S7). Next, the correction signal generator 30 generates a correction coefficient β (T) (step S8). Next, the signal correction unit 31 corrects the output signal of the Hall element 21 using the correction coefficient β (T) (step S9).
That is, in the step (B) executed at the time of magnetic field measurement, a correction signal for correcting the output of the Hall element by the correction signal generation unit 30 based on the output of the temperature sensor 26 and the information on the temperature characteristics of the Hall element. And a step of correcting the output signal of the Hall element by the signal correction unit 31 using the correction signal.
Further, β can be calculated from the constant current sensitivity at 25 ° C. and 150 ° C. as shown in Equation (6).

Further, β (T) generated by the correction signal generation unit 30 can be obtained by Expression (7). Further, F (B) that is an output signal can be obtained by Expression (8).

If the temperature characteristic of the constant current sensitivity is linear with respect to the temperature, the output signal F (B) is a value proportional to the magnetic field B and a value that does not depend on the constant current sensitivity as shown in Equation (9). Become. Therefore, the magnetic field B can be calculated with high accuracy regardless of variations in the constant current sensitivity SI of the Hall elements.

In the above formulas (7) to (9), β (T), S (T), SI (T), and F (B) are calculated based on a temperature of 25 ° C., but the temperature is limited to 25 ° C. Any temperature may be used as the reference temperature.
FIG. 8 shows the result of calculating the residual correction error by performing the signal correction method shown in the block diagram of FIG. 5 and FIG. 7 using Hall elements having different n-type impurity concentrations. In addition, the distribution depth D of the Hall element used in FIG. 8 is 10 μm or more.

FIG. 8 is a diagram showing the relationship of the residual correction error with respect to the n-type impurity concentration.
Currently, a commercially available high-precision magnetic sensor has a residual correction error of about 1.8 to 2.0%. In the future, it is considered that the remaining correction error required for a more accurate magnetic sensor is about 1.0%. From the results shown in FIG. 8, the error when the magnetic field B is calculated using the block configuration diagram shown in FIG. 5 and the signal correction method shown in FIG. Is 3.0 × 10 ¹⁴ <N <1.0 × 10 ¹⁶ (atoms / cm ³ ). That is, the magnetic sensitivity of the Hall element in the region where the n-type impurity concentration is 3.0 × 10 ¹⁴ <N <1.0 × 10 ¹⁶ (atoms / cm ³ ) is highly linear with respect to temperature.

When it is necessary to reduce the error to 1% or less by using a Hall element having an n-type impurity concentration of 1.0 × 10 ¹⁶ (atoms / cm ³ ) or more, the correction residual error is large in the linear approximation. As shown in FIG. 5, it is necessary to perform measurement before shipment at a plurality of temperatures, and to perform correction such as polygonal line approximation in many temperature regions. Pre-shipment measurement at multiple temperatures leads to an increase in test costs, and a polyline approximation in many temperature regions leads to an increase in circuit scale.

The reason why the n-type impurity concentration is 3.0 × 10 ¹⁴ <N <1.0 × 10 ¹⁶ (atoms / cm ³ ) so that the magnetic sensitivity of the Hall element is more linear with respect to temperature. Will be explained. The magnetic sensitivity of the Hall element can be expressed by Equation (10).

  G is called a shape factor, and is a parameter determined by the layout of the Hall elements. γH (T) is the Hall scattering coefficient, d (T) is the effective thickness of the Hall element, n (T) is the carrier density of the conduction band, and q is the charge of the electrons. The reason why the magnetic sensitivity of the Hall element exhibits the secondary characteristic is that the carrier density n (T) of the conduction band exhibits the secondary characteristic, but the influence of n (T) is reduced by reducing the n-type impurity concentration. Can be reduced. When the n-type impurity concentration is reduced, the influence of n (T) is reduced, and the influence of the hole scattering coefficient γH (T) becomes dominant. Since the Hall scattering coefficient γH (T) is highly linear, as a result, the linearity of the magnetic sensitivity of the Hall element can be improved by reducing the n-type impurity concentration.

It was shown that when the n-type impurity concentration is 3.0 × 10 ¹⁴ <N <1.0 × 10 ¹⁶ (atoms / cm ³ ), the correction residual error is 1.0%. However, the effect of the depletion layer is increased by reducing the n-type impurity concentration. Since the Hall element has a structure in which the periphery of the n-type impurity region is surrounded by the p-type impurity region, there are np connection regions in each direction around the magnetic sensing portion, and a depletion layer is generated. Since the depletion layer extends to a region having a low concentration, the influence of the depletion layer is increased by reducing the n-type impurity concentration of the magnetosensitive portion.

  FIG. 9 is a schematic cross-sectional view during the operation of the Hall element, showing the relationship between the distribution depth in the n-type impurity region and the depletion layer. Reference numeral 4 in the figure indicates a depletion layer. In particular, the influence of the deep portion of the n-type impurity region 2 shown in FIG. The constant current sensitivity is inversely proportional to the hole thickness d shown in FIG. 9, as shown by the equation (10). The hole thickness d is a portion obtained by subtracting the thickness of the depletion layer 4 from the distribution depth D of the n-type impurity concentration. That is, the hole thickness d decreases as the depletion layer 4 increases, and the hole thickness d increases as the depletion layer 4 decreases.

Although the influence of the depletion layer 4 is different depending on the driving method, the case of using FIG. 1 which is the most commonly used driving method will be considered. As the temperature increases, the resistance value of the Hall element increases. In the case of constant current driving in FIG. 1, the potential at point B in FIG. 1 decreases as the resistance value of the Hall element increases.
Since the average potential of the magnetic sensing portion of the Hall element may be considered as the average of the potentials at points A and B in FIG. 1, the average potential of the magnetic sensing portion decreases as the temperature increases. The depletion layer 4 is generated in the np connection region, and the width of the depletion layer 4 is determined by the difference between the potential of the n region and the potential of the p region.

  In the case of a deep portion of the n-type impurity region 2 shown in FIG. 9, the p region is the potential of the Si substrate and is GND (0 V) regardless of the temperature. The n region is an average potential of the magnetosensitive portion and changes depending on the temperature. That is, since the difference between the potential of the n region and the potential of the p region varies with temperature, the width of the depletion layer 4 also varies with temperature. Since the width of the depletion layer 4 varies with temperature, the hole thickness d also varies with temperature. Therefore, the constant current sensitivity is also affected by the temperature dependence of the hole thickness d.

If the distribution depth D of the n-type impurity region 2 is sufficiently large, the hole thickness d is hardly affected even if the width of the depletion layer 4 is changed, but if the distribution depth D is small, the depletion is not caused. The hole thickness d changes due to the change of the layer 4, which causes a decrease in linearity of the constant current sensitivity with respect to temperature.
When the temperature correction of a product whose specification temperature range is −40 to 150 ° C. is performed by two-point linear approximation, there are generally two types, and linear approximation is performed by measuring two points of −40 ° C. and 150 ° C. And a case where two points of 25 ° C. and 150 ° C. near room temperature are measured and linear approximation is performed. Measuring the two points of −40 ° C. and 150 ° C. and performing linear approximation can realize high-precision magnetic field detection over the entire temperature range of the specification. On the other hand, if two points of 25 ° C. and 150 ° C. are measured and linearly approximated, cooling is not required and the cost is reduced.

  When the two points of −40 ° C. and 150 ° C. were measured and linearly approximated, a region where the correction residual error was 1% or less was obtained. The area is expressed by Equation (11). By setting the concentration N and the distribution depth D of the n-type impurity region in this range, it is possible to realize high-precision magnetic field detection by linear approximation.

  Furthermore, when two points of 25 ° C. and 150 ° C. were measured and linearly approximated, a region where the residual correction error was 1% or less was obtained. The area is expressed by Equation (12). By setting the concentration N and the distribution depth D of the n-type impurity region in this range, it is possible to realize high-precision magnetic field detection by linear approximation. The area of the formula (12) is smaller than the area of the formula (11). By using the area of the formula (12), it is possible to realize high-precision magnetic field detection at a lower cost.

Specific examples of results within and outside the above range are shown (Example 6; Tables 1 to 19).
FIG. 10 is a diagram showing the relationship between the distribution depth D and the n-type impurity region concentration N. In FIG. The impurity concentration N and the distribution depth D of a to s shown in Tables 1 to 19 correspond to a to s in FIG. In Tables 1 to 19, the first row is the temperature, the second row is the constant current sensitivity before correction (25 ° C. standardization), the third row is the result of measuring the magnetic sensitivity at two temperatures of −40 degrees and 150 degrees. The constant current sensitivity after correction of the constant current sensitivity before correction using the temperature proportionality coefficient of the obtained constant current sensitivity is obtained from the result of measuring the magnetic sensitivity at two temperatures of 25 degrees and 150 degrees in the fourth row. It is a constant current sensitivity after correcting the constant current sensitivity before correction using the temperature proportional coefficient of current sensitivity.

In Tables 1 to 19, the concentration N indicates the impurity concentration N, and the depth D indicates the distribution depth D.
The bottom row shows the result of calculating the residual correction error in the form of ± 0%.
For example, in the case of Table 1, the maximum magnetic sensitivity SI _MAX of the fourth column (25 degrees to 150 degrees linear approximation) is 1.004, and the minimum magnetic sensitivity SI _MIN is 0.962.
Therefore, the remaining correction error E _R is (1.004−0.962) / 2.

First, point a is outside the scope of the present invention, as can be seen from FIG. Actually, when the residual correction error is calculated, it is ± 1% or more. A point where the depth is doubled at the same density N is point b. When linear approximation is performed at -40 to 150 ° C, both are ± 1% or less when linear approximation is performed at 25 to 150 ° C.
Next, the points c to e are the results when the distribution depth D is changed with the same concentration N. The point c is out of the range, the point d is within the range of the equation (11), and the point e is the equation ( 12). The remaining correction error is ± 1% or more at point c, ± 1% or less when linearly approximated at −40 to 150 ° C. at point d, and ± 1% or less when linearly approximated at 25 to 150 ° C. at point e. ing.

At the point f, when linear approximation is performed at −40 to 150 ° C., the remaining correction error is 1% or less, but when linear approximation is performed at 25 to 150 ° C., the remaining correction error is 1% or more.
Next, the point g falls outside the scope of the present invention. When the remaining correction error is calculated, it is ± 1% or more. When the correction remaining error is calculated at the point h, it can be seen that it is ± 1% or more. The point i is obtained by slightly increasing the density N at the point h. When the residual correction error is calculated, it is ± 1% or less when linear approximation is performed at −40 to 150 ° C. When the correction residual error is calculated for the j point, it can be seen that when linear approximation is performed at −40 to 150 ° C., when linear approximation is performed at 25 to 150 ° C., both are ± 1% or less.

It can be seen that the k point and the L point are points within the present invention (L) and outside (k) in the region where the distribution depth D is the largest and the density is low.
The points m to o are points on the dark side where the concentration N is within the range of the present invention. As shown in Tables 13 to 15, the remaining correction error is ± 1% or less.
Further, the points p to s are points on the side where the concentration N outside the present invention is deep. As shown in Tables 16 to 19, the remaining correction error is greater than ± 1%.

  As shown in the above results, it can be seen that there is a difference in the residual correction error after linear approximation within and outside the ranges of the formulas (11) and (12).

As described above, it is preferable that the influence of the depletion layer on the portion where the n-type impurity region and the p-type impurity region are in contact is small. Similarly, it is desirable that the influence of the depletion layer on the surface of the Hall element is small or there is no depletion layer.
FIG. 11 is a schematic sectional view of the Hall element during operation. As shown in FIG. 11, a cover layer is provided on the surface of the Hall element for insulation from the upper layer. In order to increase the value of the hole thickness d as much as possible, the influence of the depletion layer is required to be small at the connection portion between the cover layer and the n-type impurity region. Therefore, the cover layer is preferably silicon oxide. The purpose of the cover layer can be achieved if insulation other than silicon oxide can be achieved, but if the depletion layer is generated, the hole thickness d is reduced. When a large depletion layer is generated at the connection portion between the cover layer and the n-type impurity region, the distribution depth D needs to be set to a large value in order to obtain the same hole thickness d as when there is no depletion layer. Therefore, silicon oxide that does not generate a depletion layer is desirable as the cover layer of the Hall element.

The n-type impurity region is generally formed by epitaxial growth or thermal diffusion of an implant implanted in a silicon substrate. In both methods, in order to increase the distribution depth D, it is necessary to lengthen the manufacturing time.
The thermal diffusion of the implant is determined by the type of implant, the heating temperature and the heating time. The type of implant is generally P (phosphorus) as an n-type impurity, but is not limited to this as long as it is a material serving as a donor. When a general manufacturing method is used, if the heating time is about 1500 minutes, the distribution depth is about 15 μm.

  By increasing the heating time, the distribution depth can be increased. From the viewpoint of manufacturing time, the heating time is preferably 1500 minutes or less, and the distribution depth is preferably 15 μm or less. . From the viewpoint of manufacturing time, the distribution depth D is preferably 10 μm or less, more preferably 9 μm or less, still more preferably 8 μm or less, and particularly preferably 7 μm or less. Further, the distribution depth D may be 6 μm or less, or 5 μm or less.

In order to reduce the influence of the depletion layer generated between the n-type impurity region and the p-type impurity region on the magnetic sensitivity, the distribution depth D is preferably 3 μm or more, and preferably 4 μm or more. More preferably, it is 5 μm or more.
Further, B (boron) is generally used as the p-type impurity used in the p-type impurity region around the Hall element, but it is not limited to this as long as it is a material serving as an acceptor. The impurity concentration of the p-type impurity region is not particularly limited, and may be 1.0 × 10 ¹⁴ (atoms / cm ³ ) or more and 1.0 × 10 ²¹ (atoms / cm ³ ) or less which is a general impurity concentration. Good.

  From the above results, in order to realize a low-cost and highly accurate magnetic sensor, the n-type impurity concentration N and the distribution depth D that satisfy Equation (3) are desirable, and the n-type impurity concentration that satisfies Equation (4) is also desirable. N and the distribution depth D are more desirable. FIG. 4 illustrates the range represented by the mathematical formulas (3) and (4). By appropriately correcting the Hall element manufactured in the range shown in FIG. 4 such as a two-point temperature linear approximation, it becomes possible to realize a magnetic sensor having high magnetic field detection accuracy at low cost. .

In the second embodiment, by limiting the n-type impurity concentration N and the distribution depth D and performing multipoint correction, the correction residual error after correction can be reduced as compared with the conventional Hall element and multipoint correction. Can do.
In the first embodiment described above, a method of correcting by performing a two-point straight line approximation in the pre-shipment inspection is adopted. In addition, when high-precision correction is required, it is effective to measure the constant current sensitivity at three temperatures of -40 ° C, 25 ° C, and 150 ° C during the pre-shipment inspection, and perform correction using the three-point broken line approximation. is there. The block diagram for explaining the magnetic sensor in the second embodiment is the same as that in the first embodiment.

FIG. 12 is a flowchart for explaining the second embodiment of the signal correction method of the magnetic sensor according to the present invention shown in FIG. 5, and shows a flow of correction from inspection before shipment. The signal correction method for the magnetic sensor in the second embodiment includes a step (A) for performing a test before shipment and a step (B) for performing the magnetic field measurement.
In the step (A) for performing the test before shipment, first, the first constant current sensitivity SI25 at the first temperature of 25 ° C. is measured (step S11). Next, the second constant current sensitivity SI150 at the second temperature of 150 ° C. is measured (step S12). Next, a third constant current sensitivity SI-40 at a third temperature of −40 ° C. is measured (step S13). Next, the slope β1 is calculated from the first constant current sensitivity SI25 and the third constant current sensitivity SI-40 (step S14). Next, the slope β2 is calculated from the first constant current sensitivity SI25 and the second constant current sensitivity SI150 (step S15). Next, the inclination β1 and the inclination β2 are stored in the temperature proportional coefficient storage unit 28 (step S16). Next, the first constant current sensitivity SI25 is stored in the magnetic sensitivity storage unit 29 (step S17).

In the step (B) executed at the time of magnetic field measurement, first, the temperature T is measured by the temperature sensor 26 (step S18). Next, the temperature T is AD converted (step S19). Next, the correction signal generator 30 generates a correction coefficient β (T) (step S20). Next, the signal correction unit 31 corrects the output signal of the Hall element 21 using the correction coefficient β (T) (step S21).
That is, in the step (B) executed at the time of magnetic field measurement, first, the step of acquiring information on the temperature characteristics of the Hall element by the temperature sensor 26, and then the output of the temperature sensor 26 and the information on the temperature characteristics of the Hall element. And a step of generating a correction signal for correcting the output of the Hall element by the correction signal generation unit 30, and a step of correcting the output signal of the Hall element by the signal correction unit 31 using the correction signal, have.

That is, β ₁ and β ₂ calculated in the correction coefficient calculation block of FIG. 12 can be obtained by Expression (12).

FIG. 13 is a diagram showing the relationship of the residual correction error with respect to the n-type impurity concentration, and shows the result of obtaining the residual correction error (three-point broken line approximation error) after correction by the three-point broken line approximation. When the n-type impurity concentration N is 7.0 × 10 ¹⁴ <N <1.0 × 10 ¹⁶ (atoms / cm ³ ), the remaining correction error can be reduced to 0.2%.
Since the region of the distribution depth D when the depletion layer region is taken into consideration is the same as that of the first embodiment described above, a magnetic sensor having a high magnetic field detection accuracy can be realized using the three-point broken line approximation. The n-type impurity concentration N and the distribution depth D that satisfy Equation (3) are desirable, and the n-type impurity concentration N and the distribution depth D that satisfy Equation (4) are more desirable. FIG. 4 illustrates the range.

  In addition, as the constant current sensitivity is decreased, the secondary temperature characteristic at a high temperature tends to be relatively visible instead of decreasing the secondary temperature characteristic at a low temperature as the n-type impurity concentration N is decreased. In order to correct the secondary temperature characteristic at a high temperature with higher accuracy, it is better to perform multipoint correction of three or more points. Compared to the case where the n-type impurity concentration N is high, the correction error after multipoint correction is smaller in the range of the n-type impurity concentration shown in Equation (3) or Equation (4), and a more accurate magnetic sensor. Can be realized.

In the first and second embodiments described above, an example of 4 Phase chopper driving is shown, but in this third embodiment, an example of 2 Phase chopper driving is shown. When this 2 Phase chopper drive is used, the residual offset increases. The distribution depth D that can reduce the residual offset is defined (D ≧ 4 μm).
That is, in the first embodiment and the second embodiment described above, an example is shown in which the offset is dynamically removed by 4 Phase chopper driving. However, when high speed response such as a current sensor is required, 2 Phase chopper driving is used. The 2 Phase chopper drive has excellent responsiveness because the measurement time for one cycle is shorter than that of the 4 Phase chopper drive.

  An example of 2 Phase chopper drive is as follows: a Hall drive current is passed from electrode 1 to electrode 3 in Phase 1, an electrode 2-electrode 4 is connected to a differential amplifier, and a Hall drive current is passed from electrode 2 to electrode 4 in Phase 2. The driving procedure is to connect the electrode 3-electrode 1 to the differential amplifier.

  Although the offset can be removed even by the 2Phase chopper drive, the effect of removing the offset is inferior to that of the 4Phase chopper drive. As a method of reducing the residual offset remaining after driving the 2 Phase chopper, there is a method of increasing the diffusion time of the implant and increasing the uniformity of the implant in the n-type impurity region. Increasing the diffusion time of the implantation increases the distribution depth D of the n-type impurity region.

FIG. 14 is a diagram illustrating the relationship between the distribution depth and the residual offset variation in the third embodiment. It can be seen that, when the distribution depth is D4 μm or less, the variation in the residual offset at the time of the 2 Phase chopper increases rapidly. For this reason, it is desirable that the n-type impurity concentration and distribution depth satisfy Equation (15) when the 2 Phase chopper is driven.
FIG. 15 is a diagram illustrating the relationship between the distribution depth and the n-type impurity region concentration, and is a diagram illustrating the range represented by Equation (15).

In the first embodiment described above, the two-point linear correction is performed (inclination β is calculated for each sample). However, the fourth embodiment is a representative value of the inclination β with respect to the temperature of the one-point correction + constant current sensitivity. Correction (only one point is calculated for each sample). The fourth embodiment is inferior in magnetic field detection accuracy to the first embodiment described above, but can achieve low cost.
In the conventional n-type impurity concentration and distribution depth of the Hall element, the correction residual error was large when corrected with the representative value of the slope β. However, in the range of the Hall element of the present invention, the correction was made with the representative value of the slope β. However, the residual correction error is not large.

Further, by setting the n-type impurity concentration N and the distribution depth D in the range of the formula (3) or the formula (4), it is possible to realize a highly accurate magnetic sensor only by correcting the absolute value of one point temperature. Become. The block diagram for explaining the magnetic sensor in the fourth embodiment is the same as in the first and second embodiments described above.
FIG. 16 is a flowchart for explaining the fourth embodiment of the signal correction method of the magnetic sensor according to the present invention shown in FIG. The signal correction method of the magnetic sensor in the fourth embodiment includes a step (A) of measuring a flow rate of a product in advance and determining a slope β of the constant current sensitivity with respect to a temperature and a step of performing a pre-shipment test on each sample (B). And a step (C) executed at the time of magnetic field measurement.

In the step (A) for performing the test before shipment, first, the first constant current sensitivity SI25 at the first temperature of 25 ° C. is measured (step S31). Next, the second constant current sensitivity SI150 at the second temperature of 150 ° C. is measured (step S32). Next, the slope β of the constant current sensitivity with respect to the temperature is calculated from the first constant current sensitivity SI25 and the second constant current sensitivity SI150 (step S33).
In the step (B) of performing the pre-shipment test on each sample, first, the first constant current sensitivity SI25 at the first temperature of 25 ° C. is measured (step S34). Next, the first constant current sensitivity SI25 is stored in the magnetic sensitivity storage unit 29 (step S35). Next, the gradient β obtained by the flow measurement is stored in the temperature proportional coefficient storage unit 28 (step S36).

In the step (C) executed at the time of magnetic field measurement, first, the temperature T is measured by the temperature sensor 26 (step S37). Next, the temperature T is AD converted (step S38). Next, the correction signal generator 30 calculates a correction coefficient β (T) (step S39). Next, the signal correction unit 31 corrects the output signal of the Hall element 11 using the correction coefficient β (T) (step S40).
That is, in the process executed at the time of magnetic field measurement, first, based on the step of obtaining information on the temperature characteristics of the Hall element by the temperature sensor 26, and then on the output of the temperature sensor 26 and the information on the temperature characteristics of the Hall element. The correction signal generation unit 30 generates a correction signal for correcting the output of the Hall element, and the signal correction unit 31 corrects the output signal of the Hall element using the correction signal. ing.

  In the first embodiment described above, the constant current sensitivity at the two-point temperature is measured in each sample, and the slope β of the constant current sensitivity with respect to the temperature is calculated. In the fourth embodiment, the constant current sensitivity with respect to the temperature is calculated. The slope β is corrected using the representative value of the flow result. In this case, in order to calculate β, it is necessary to perform inflow in advance. However, since it is only necessary to measure the constant current sensitivity at one point temperature in each sample, the test cost can be reduced. Although the accuracy of the slope β with respect to the temperature of the constant current sensitivity is inferior to that of the first embodiment described above, by setting the n-type impurity concentration N and the distribution depth D within the range of the formula (3) or the formula (4). Therefore, it is possible to suppress deterioration in accuracy of the slope β.

FIG. 17 is a diagram showing the relationship of the temperature characteristic variation of the constant current sensitivity with respect to the n-type impurity concentration. Compared with the case where β is calculated for each sample, the results show how much accuracy is deteriorated when correction is made using the representative value β of the flow-in result. As can be seen from the result of FIG. 17, in the region where the n-type impurity concentration is 1.0 × 10 ¹⁶ (atoms / cm ³ ) or more, the accuracy is rapidly deteriorated, whereas the n-type impurity concentration is 1.0. It can be seen that accuracy degradation is suppressed in a region of less than × 10 ¹⁶ (atoms / cm ³ ).

  That is, conventionally, as in Patent Document 3 described above, the temperature characteristics of the constant current sensitivity are approximated by multipoint broken lines to ensure accuracy, but the n-type impurity concentration N and the distribution depth D are expressed by Equation (3). Alternatively, by setting the range of the mathematical formula (4), it becomes possible to ensure the accuracy only by calculating the slope of the constant current sensitivity with respect to the temperature and measuring the constant current sensitivity at one point temperature in advance. A magnetic sensor having high magnetic field detection accuracy can be realized.

In the first to fourth embodiments described above, the correction is performed in the subsequent stage of the integrator 15, but the correction may be performed in the previous stage of the integrator 15. Further, a correction signal may be output outside the magnetic sensor IC and the correction calculation may be performed outside the IC. Furthermore, since the relative signal proportional to the magnetic field B, may be carried out correction calculation, the correction to the constant current sensitivity SI, correction with respect to the drive current I _H of the Hall element, the correction to the magnetic field strength B, the magnetic field You may correct | amend with respect to the signal XB proportional to the intensity | strength B. FIG. That is, the physical quantity based on the Hall electromotive force includes correction, and the physical quantity based on the Hall electromotive force includes the Hall electromotive force signal VH, the constant current sensitivity SI (T), the Hall driving current IH, the magnetic field B, and each physical quantity. Can be included in an amount proportional to.

As described above, by using the Hall element of the present invention, a Hall element including a p-type impurity region and an n-type impurity region provided on the p-type impurity region and functioning as a magnetic sensing portion, and two or more points Based on a temperature characteristic storage unit storing information about the temperature characteristics of the Hall element calculated from the output of the Hall element measured at a temperature of 5 points or less, the output of the temperature sensor, and the information about the temperature characteristic of the Hall element The correction signal generation unit that generates a correction signal for correcting the output of the Hall element, the correction signal generated by the correction signal generation unit, and the output signal of the Hall element are input, and based on the correction signal, A magnetic sensor including a signal correction unit that corrects an output signal and outputs a corrected output signal of the Hall element. The magnetic sensor has a predetermined magnitude and a magnetic field in a predetermined direction at 25 degrees. A value signal indicating output from the signal correction unit when applied to the magnetic sensor under degrees environment V _25, a predetermined size and a magnetic field in a predetermined direction to the magnetic sensor over a temperature environment of 150 ° -40 ° E _R = ((V _MAX / V ₂₅ ) − (V _MIN ) when the largest value is V _MAX and the smallest value is V _MIN among the values indicated by the signal output from the signal correction unit when applied. _/ V ₂₅₎₎ / 2 corrected residue error E _R represented by it is possible to provide a magnetic sensor, characterized in that 1.0% or less.

Also, a Hall element provided with a p-type impurity region and an n-type impurity region provided on the p-type impurity region and functioning as a magnetic sensing portion, and an output of the Hall element measured at a temperature of 2 to 3 points A correction signal for correcting the output of the Hall element based on the temperature characteristic storage unit storing information on the temperature characteristic of the Hall element calculated from the above, the output of the temperature sensor, and the information on the temperature characteristic of the Hall element. The correction signal generation unit to be generated, the correction signal generated by the correction signal generation unit, and the output signal of the Hall element are input, the output signal of the Hall element is corrected based on the correction signal, and the corrected output signal of the Hall element A signal correction unit that outputs a magnetic field of a predetermined magnitude and direction when a magnetic field in a predetermined direction is applied to the magnetic sensor in a temperature environment of 25 degrees. A value indicating the signal output is V _25, the predetermined size and the predetermined value indicated by the signal output from the signal correction unit when applied to a magnetic sensor for under 150 degrees temperature environment from 25 ° field direction Of these, the remaining correction error E represented by E _R = ((V _MAX / V ₂₅ ) − (V _MIN / V ₂₅ )) / 2, where V _{MAX is} the largest value and V _MIN is the smallest value. It is possible to provide a magnetic sensor characterized in that _R is 1.0% or less.

  In the above-described embodiment, the description has been made centering on the example of calculating the information on the temperature characteristics of the Hall element from the output of the Hall element measured at two or three temperatures. However, the present invention is not limited to this. The information regarding the temperature characteristics of may be calculated from the output of the Hall element measured at four or more temperatures. However, on the relationship of man-hours required to calculate the information on the temperature characteristics of the Hall element, the information on the temperature characteristics of the Hall element is preferably calculated from the output of the Hall element measured at a temperature of 5 points or less, It is more preferable to calculate from the output of the Hall element measured at a temperature of 4 points or less, and it is particularly preferable to calculate from the output of the Hall element measured at a temperature of 3 points or less.

  In the above embodiment, the temperature proportionality coefficient β has been mainly described as an example of calculating from the magnetic sensitivity of the Hall element measured at two or three temperatures. However, the temperature proportionality coefficient β is a temperature of four or more points. It may be calculated from the measured magnetic sensitivity of the Hall element. However, the temperature proportionality coefficient β is preferably calculated from the magnetic sensitivity of the Hall element measured at a temperature of 5 points or less because of the number of steps required to calculate the temperature proportionality coefficient β. It is more preferable to calculate from the measured magnetic sensitivity of the Hall element, and it is particularly preferable to calculate from the magnetic sensitivity of the Hall element measured at a temperature of 3 points or less.

  As described above, according to the present invention, the concentration and depth of the n-type impurity region, which is the magnetic sensing portion of the Hall element, are limited to an appropriate range, so that the magnetic field strength can be detected with high accuracy in a straight line of temperature characteristics. By improving the performance, a Hall element, a magnetic sensor including the Hall element, and a signal correction method thereof can be realized.

1 p-type impurity region 2 n-type impurity region (magnetic part)
DESCRIPTION OF SYMBOLS 3 Electrode part 4 Depletion layer 21 Hall element 22 Hall drive current source 23 Chopper switch part 24 Differential amplifier 25 Integrator 26 Temperature sensor 27 Analog-digital converter (ADC)
28 Temperature proportional coefficient memory (EEPROM)
29 Magnetic sensitivity storage (EEPROM)
30 Correction signal generation unit 31 Signal correction unit 32 Temperature characteristic storage unit

Claims (32)

A magnetic sensor comprising a Hall element having a p-type impurity region and an n-type impurity region provided on the p-type impurity region and functioning as a magnetic sensitive part,
The n-type impurity concentration N (atoms / cm ³ ) and the distribution depth D (μm) of the n-type impurity region are:
N <1.0 × 10 ¹⁶
N> 3.802 × 10 ¹⁶ × D ^−1.761
(However, the n-type impurity concentration N is the maximum concentration of the n-type impurity concentration in the n-type impurity region, and the distribution depth D is determined from the point that the n-type impurity concentration becomes maximum. (This is the length in the depth direction up to the point where the impurity concentration is 1/10 of the concentration.)
Meet the relationship,
A temperature characteristic storage unit storing information on the temperature characteristic of the Hall element;
A correction signal generating unit that generates a correction signal for correcting the output of the Hall element based on the output of the temperature sensor and information on the temperature characteristics of the Hall element;
A signal correction unit that receives the correction signal generated by the correction signal generation unit and the output signal of the Hall element, and corrects the output signal of the Hall element based on the correction signal;
Magnetic sensor equipped with . The magnetic sensor according to claim 1, wherein the n-type impurity concentration N and the distribution depth D satisfy a relational expression of N> 3.410 × 10 ¹⁶ × D− ^1.293 . The magnetic sensor according to claim 1, wherein the distribution depth D satisfies a relational expression of D ≦ 15. The magnetic sensor according to claim 1, wherein the distribution depth D satisfies a relational expression of 4 ≦ D. The magnetic sensor according to claim 1, further comprising a silicon oxide layer covering the n-type impurity region. The magnetic sensor according to claim 5, wherein the n-type impurity region is in contact with the silicon oxide layer. The magnetic sensor according to claim 1, wherein the n-type impurity concentration N satisfies a relational expression of 3.0 × 10 ¹⁴ <N. The temperature characteristic storage unit is
A temperature proportional coefficient storage unit that stores information on a temperature proportional coefficient of magnetic sensitivity of the Hall element;
A magnetic sensitivity storage unit that stores information related to magnetic sensitivity at a predetermined temperature of the Hall element,
Information regarding the temperature characteristics of the Hall element, and the information regarding the temperature coefficient of proportionality magnetic sensitivity of the Hall element, according to claim 1 including the information about the magnetic sensitivity at a given temperature of the Hall element Magnetic sensor. The information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element stored in the temperature proportionality coefficient storage unit is information on the temperature proportionality coefficient of the constant current sensitivity of the Hall element,
The magnetic sensor according to claim 8 , wherein the information on the magnetic sensitivity at a predetermined temperature of the Hall element stored in the magnetic sensitivity storage unit is information on a constant current sensitivity of the Hall element at the predetermined temperature. The information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element includes the first magnetic sensitivity of the Hall element measured at a first temperature and the second magnetic sensitivity of the Hall element measured at a second temperature. The magnetic sensor according to claim 8 , wherein the magnetic sensor is information calculated from: The first magnetic sensitivity is a constant current sensitivity of the Hall element measured at the first temperature, and the second magnetic sensitivity is a constant current of the Hall element measured at the second temperature. The magnetic sensor according to claim 10 , which is a sensitivity. The information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element further includes the first magnetic sensitivity, the second magnetic sensitivity, and the third magnetic sensitivity of the Hall element measured at the third temperature. The magnetic sensor according to claim 10 , wherein the magnetic sensor is information calculated from: The magnetic sensor according to claim 12 , wherein the third magnetic sensitivity is a constant current sensitivity of the Hall element measured at the third temperature. 14. The magnetism according to claim 8 , wherein the information regarding the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is calculated from the magnetic sensitivity of the Hall element measured at a temperature of 2 to 5 points. Sensor. The magnetic sensor according to claim 14 , wherein the information regarding the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is calculated from the magnetic sensitivity of the Hall element measured at a temperature of 2 points or more and 3 points or less. Information regarding the temperature characteristics of the Hall element, a magnetic sensor according to any of claims 1 to 15, which is calculated from the output of said measured Hall element at a temperature below 5 points or more 2 points. 17. The magnetic sensor according to claim 16 , wherein the information on the temperature characteristics of the Hall element is calculated from the output of the Hall element measured at a temperature of 2 to 3 points. A signal correction method for a magnetic sensor according to any one of claims 1 to 17 ,
Obtaining information on temperature characteristics of the Hall element;
Generating a correction signal for correcting the output of the Hall element based on the output of the temperature sensor and information on the temperature characteristics of the Hall element;
Obtaining an output of the Hall element;
And correcting the output signal of the Hall element using the correction signal. The information on the temperature characteristics of the Hall element includes information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element and information on the magnetic sensitivity of the Hall element at a predetermined temperature,
Acquiring information on temperature characteristics of the Hall element according to claim 18 comprising the step of acquiring information about the magnetic sensitivity at a given temperature of the information relating to the temperature proportional coefficient of the magnetic sensitivity of the Hall element Hall element Signal correction method of the magnetic sensor. The information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is information on the temperature proportionality coefficient of the constant current sensitivity of the Hall element,
The signal correction method for a magnetic sensor according to claim 19 , wherein the information on the magnetic sensitivity of the Hall element at a predetermined temperature is information on the constant current sensitivity of the Hall element at the predetermined temperature. The information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element includes the first magnetic sensitivity of the Hall element measured at a first temperature and the second magnetic sensitivity of the Hall element measured at a second temperature. The signal correction method for a magnetic sensor according to claim 19 or 20 , wherein the information is calculated from the following information. The first magnetic sensitivity is a constant current sensitivity of the Hall element measured at the first temperature, and the second magnetic sensitivity is a constant current of the Hall element measured at the second temperature. The method of correcting a signal of the magnetic sensor according to claim 21 , wherein the signal is a sensitivity. The information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element further includes the first magnetic sensitivity, the second magnetic sensitivity, and the third magnetic sensitivity of the Hall element measured at the third temperature. The signal correction method of the magnetic sensor according to claim 21 or 22 , wherein the information is calculated from the following. The signal correction method for a magnetic sensor according to claim 23 , wherein the third magnetic sensitivity is a constant current sensitivity of the Hall element measured at the third temperature. Information about the temperature-proportional coefficient of the magnetic sensitivity of the Hall element according to any one of claims 19 to 24, which is calculated from the magnetic sensitivity of said measured Hall element at a temperature below 5 points or more 2 points magnetic Sensor signal correction method. 26. The signal correction method for a magnetic sensor according to claim 25 , wherein the information related to the temperature proportionality coefficient of the magnetic sensitivity of the Hall element is calculated from the magnetic sensitivity of the Hall element measured at a temperature of 2 to 3 points. 27. The signal correction method for a magnetic sensor according to claim 18 , wherein the information on the temperature characteristics of the Hall element is calculated from an output of the Hall element measured at a temperature of 2 points or more and 5 points or less. . 28. The signal correction method for a magnetic sensor according to claim 27 , wherein the information related to the temperature characteristics of the Hall element is calculated from the output of the Hall element measured at a temperature of 2 to 3 points. The step of acquiring information on the temperature characteristics of the Hall element includes:
Measuring a first magnetic sensitivity of the Hall element at a first temperature;
Measuring a second magnetic sensitivity of the Hall element at a second temperature;
Obtaining information on a temperature proportionality coefficient of the magnetic sensitivity of the Hall element from the first magnetic sensitivity and the second magnetic sensitivity,
Based on the output of the temperature sensor and information on the temperature characteristics of the Hall element, generating a correction signal for correcting the output of the Hall element,
A correction signal for correcting the output of the Hall element is generated based on the output of the temperature sensor, the information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element, and the magnetic sensitivity of the Hall element at a predetermined temperature. The method of correcting a signal of a magnetic sensor according to claim 18 , wherein The step of acquiring information on the temperature characteristics of the Hall element includes:
Measuring a first magnetic sensitivity of the Hall element at a first temperature;
Measuring a second magnetic sensitivity of the Hall element at a second temperature;
Measuring a third magnetic sensitivity of the Hall element at a third temperature;
Obtaining information on the temperature proportionality coefficient of the magnetic sensitivity of the Hall element from the first magnetic sensitivity, the second magnetic sensitivity, and the third magnetic sensitivity,
Based on the output of the temperature sensor and information on the temperature characteristics of the Hall element, generating a correction signal for correcting the output of the Hall element,
A correction signal for correcting the output of the Hall element is generated based on the output of the temperature sensor, the information related to the temperature proportionality coefficient of the magnetic sensitivity of the Hall element, and the magnetic sensitivity of the Hall element at a predetermined temperature. The method for correcting a signal of a magnetic sensor according to claim 18 , which is a step. The signal correction method for a magnetic sensor according to claim 29 or 30 , wherein the magnetic sensitivity is constant current sensitivity. The step of obtaining information on the temperature characteristics of the Hall element is a process performed before shipment,
Generating a correction signal for correcting the output of the Hall element based on the output of the temperature sensor and information on the temperature characteristics of the Hall element;
Obtaining an output of the Hall element;
The step of correcting the output signal of the Hall element using the correction signal,
The method for correcting a signal of a magnetic sensor according to any one of claims 18 to 31 , which is a step executed at the time of magnetic field measurement.

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